1. Technical Field
The present invention relates to green roof technology and more particularly to a modular interlocking system which provides pre-vegetated units for building rooftops.
2. Description of the Related Art
Green roofs include a system of manufactured layers placed over rooftops to support growing medium and vegetation. Green roofs or sod roofs have been around for centuries. With the effects of global warming, pollution and other modern environmental issues, a renewed trend has begun for green roofs.
Many green roofs are installed to and need to comply with local regulations, often regarding storm water runoff management. In areas with combined sewer-storm water systems, heavy storms can overload the wastewater system and cause it to flood, dumping raw sewage into the local waterways. Green roofs decrease the total amount of runoff and slow the rate of runoff from the roof. It has been found that they can retain up to 75% of rainwater, gradually releasing it back into the atmosphere via condensation and transpiration, while retaining pollutants in their soil. In this way, green roofs can buffer acid rain and other pollutants. An issue that arises is how much weight can be placed on a roof as roofs have loading limitations.
Combating the urban heat island effect is another reason for creating a green roof. Traditional building materials soak up the sun's radiation and re-emit it as heat, making cities at least 4 degrees Celsius (7° F.) hotter than surrounding areas. Green roof temperatures on a hot day are typically 14-44 degrees Celsius (25-80° F.) cooler than they are on traditionally roofed buildings nearby. It has now been estimated that if all the roofs in a major city were green, urban temperatures could be reduced by as much as 7 degrees Celsius.
Green roofs have also been found to dramatically improve a roof's insulation value (e.g., one study found that a 26% reduction in summer cooling needs and a 26% reduction in winter heat losses when a green roof is used). In addition, greening a roof is expected to lengthen a roof's lifespan by two or three times because the roof's waterproofing membrane is protected from the sun's UV and quick changes in temperature. Greening a roof can also dramatically reduce indoor noise pollution, which is extremely beneficial to the quality of life in urban areas.
Rooftop water purification is also being implemented in green roofs. These forms of green roofs function as water treatment ponds built onto the rooftops. They are built either from a simple substrate or with plant-based ponds. Green roofs also provide habitats for plants, insects, and birds that otherwise have limited natural space in cities. Even in high-rise urban settings as tall as 19 stories, it has been found that green roofs can attract beneficial insects, birds, bees and butterflies. Rooftop greenery complements wild areas by providing areas for birds and other wildlife facing shortages of natural habitat.
Despite the many benefits of green roofs, it remains difficult to build gardens on rooftops. The amount of water held by the roof top garden is a major concern. A continuous bed is preferred to ensure even distribution of vegetation as well as distribute water reserves among plants. Continuous beds require soil placement on the roof with uniform and sufficient soil depth to support plant growth. In addition, moving or removing the continuous bed of soil is difficult and labor intensive. An alternative to the continuous bed is the setting of trays filled with growing media and vegetation. Tray grown plants permit the plants to be easily transported and arranged, but have many issues with water. Root rot and insufficient watering is common with plantings grown in trays. Further, planted trays on a rooftop may create a dangerous condition if the trays are not properly anchored.
Therefore, a need exists for an apparatus and system that provide for water management, easy transportability, continuous bed advantages and controlled soil heights and weight characteristics, root entanglement for erosion control, along with the ability to remove segments for service to the roof. A further need exists for a system that provides an economical means of installation and establishment of a green extensive roof.